/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.checkpoint;

import javax.annotation.Nullable;

import java.io.Serializable;

import static org.apache.flink.util.Preconditions.checkNotNull;

/**
 * Statistics for a restored checkpoint.
 */
public class RestoredCheckpointStats implements Serializable {

	private static final long serialVersionUID = 2305815319666360821L;

	/** ID of the restored checkpoint. */
	private final long checkpointId;

	/** Properties of the restored checkpoint. */
	private final CheckpointProperties props;

	/** Timestamp when the checkpoint was restored at the coordinator. */
	private final long restoreTimestamp;

	/** Optional external path. */
	@Nullable
	private final String externalPath;

	/**
	 * Creates a new restored checkpoint stats.
	 *
	 * @param checkpointId ID of the checkpoint.
	 * @param props Checkpoint properties of the checkpoint.
	 * @param restoreTimestamp Timestamp when the checkpoint was restored.
	 * @param externalPath Optional external path if persisted externally.
	 */
	RestoredCheckpointStats(
			long checkpointId,
			CheckpointProperties props,
			long restoreTimestamp,
			@Nullable String externalPath) {

		this.checkpointId = checkpointId;
		this.props = checkNotNull(props, "Checkpoint Properties");
		this.restoreTimestamp = restoreTimestamp;
		this.externalPath = externalPath;
	}

	/**
	 * Returns the ID of this checkpoint.
	 *
	 * @return ID of this checkpoint.
	 */
	public long getCheckpointId() {
		return checkpointId;
	}

	/**
	 * Returns the properties of the restored checkpoint.
	 *
	 * @return Properties of the restored checkpoint.
	 */
	public CheckpointProperties getProperties() {
		return props;
	}

	/**
	 * Returns the timestamp when the checkpoint was restored.
	 *
	 * @return Timestamp when the checkpoint was restored.
	 */
	public long getRestoreTimestamp() {
		return restoreTimestamp;
	}

	/**
	 * Returns the external path if this checkpoint was persisted externally.
	 *
	 * @return External path of this checkpoint or <code>null</code>.
	 */
	@Nullable
	public String getExternalPath() {
		return externalPath;
	}
}
